1. Field of the Invention
The invention relates to an improved heat exchanger for heating a product, in particular a composition for producing candies.
2. Description of the Prior Art
One heat exchanger of the type with which this invention is concerned is known from U.S. Pat. No. 5,246,062. In this known heat exchanger, the product is guided within parallel tubes of equal diameter disposed side by side. In the face-end closing elements of the housing jacket of the heat exchanger there are recesses, which together with the tubes form a meandering product path. The inlet for the heating medium is located in the upper part of the cylindrically embodied housing jacket, while the outlet is disposed in the lower part. A disadvantage of the known heat exchanger is that no defined flow path within the housing is created for the heating medium. Instead, the tubes that carry the product protrude transversely into the flow path of the heating medium, so that the heat transfer from the heating medium into the product, and hence the efficiency of the known heat exchanger, are not yet optimal. This is also due to idle spaces, through which heating medium flows only inadequately. Furthermore, a product when it is heated expands inside the tubes. Since the tube diameter for the product is always the same in the known heat exchanger, the pressure of the product thus increases steadily upon heating along the product path, which can lead to a shift in the boiling line of the product and to strength problems and necessitates appropriate dimensioning of the tubes.
From German Patent DE 29 07 770 C2, a heat exchanger is also known in which both the product and the heating medium are carried back and forth in a meandering course. However, a disadvantage here, among others, is its relatively complicated structure because of the various meandering flow paths.